This invention relates to a novel process for the preparation of the antihypertensive agent, compound (I) ##STR2## comprising fermentation of compound (II) ##STR3## with the Actinoplanes sp. MA6559 (ATCC 53771) or a mutant thereof. Compounds (I) and its precursor (II) are Angiotensin II (A II) receptor antagonists useful in the treatment of human hypertensive diseases.
A II is an octapeptide hormone produced mainly in the blood during the cleavage of Angiotensin I by angiotensin converting enzyme (ACE). ACE is localized on the endothelium of blood vessels of lung, kidney and many other organs. A II is the end product of the renin-angiotensin system (RAS), a system that plays a central role in the regulation of normal blood pressure and seems to be critically involved in hypertension development and maintenance, as well as congestive heart failure. A II is a powerful arterial vasconstrictor that exerts its action by interacting with specific receptors present on cell membranes. A II receptor antagonism is one of the possible modes of controlling the RAS.